1. Field of the Invention
The present invention relates to a switch apparatus characterized by its "seesaw movement" and, more particularly, to an automotive door lock switch which is mounted on a motor car or the like and which is provided with a mechanism for preventing unintentional or accidental operation.
2. Description of the Related Art
A "seesaw-type" switch is extensively used as a switch or the like for turning ON or OFF power supplied to a motor for driving a component because it survives large currents. In the seesaw-type switch, a moving contactor is rocked around a supporting point to make or break contact between the moving contactor and a fixed contact. A switch apparatus designed to operate a switch by rocking a control lever, is employed, for example, as a door lock switch for a motor vehicle.
FIG. 8 shows such a switch apparatus in actual use as the door lock switch for a motor vehicle. This type of a door lock switch 100 and a power window switch 200 sharing the same construction with the door lock switch 100 are disposed close to each other on an armrest 90 of a driver's seat.
The door lock switch 100 is located at front left of the driver's seat. The knob of the door lock switch 100 is pressed to lock or unlock the door. The power window switch 200 is located behind the door lock switch 100; it is comprised of a total of four switches, two pairs arranged in two rows, for opening and closing the right and left windows of the front seats and the right and left windows of the rear seats, respectively.
FIG. 9 is a schematic perspective view illustrative of the construction of the switch apparatus. A pair of opposing outer side lugs 101a of a shallow cylindrical case 101 with a bottom extends upward, and a control lever 105 is rotatably mounted with a shaft 102 as the center thereof between the side plates 101a. A knob 103 is mounted on the top of the control lever 105. The control lever 105 is forked and provided with four moving contactors at the bottom thereof. The control lever 105 is further provided with mounting holes in the bottom surface thereof, driving rods being housed elastically in the mounting holes through springs.
The bottom surface of the case 101 has first fixed contacts 110a, 110b and second fixed contacts 111a, 111b which are arranged in parallel. Supporting plates are fixed on the bottom surface of the case 101 approximately at the middle between the first fixed contacts 110a and 110b. Provided on the supporting plates are moving contactors 108a and 108b which are made of curved metallic band-shaped plates.
In the conventional switch apparatus, when the control lever 103 is in the neutral position, the moving contactor 108a, which is pressed by the driving rod, is in contact with the fixed contact 110b. Under such a condition, when the control lever 103 is turned clockwise, the driving rod slides on the slide surface. The sliding resistance changes and therefore a click is felt at some midpoint during the slide, and immediately after the click, the moving contactor 108a is pressed by the driving rod and rotated to come in contact with the fixed contact 110b, thus accomplishing the changeover of the switch. The driving rod also moves on the moving contact toward the fixed contact as the control lever 103 rotates, but the moving contactor remains stationary.
Conversely, when the control lever 103 is turned counterclockwise from the neutral position mentioned above, the driving rod slides on the slide surface. A click is felt when the driving rod reaches the clicking point, and immediately after the click, the moving contactor 108a is pressed by the driving rod and rotated to come in contact with the fixed contact 110a, thus accomplishing the changeover of the switch. The driving rod also moves on the moving contactor toward the fixed contact as the control lever rotates, but the moving contactor remains stationary. The conventional switch apparatus stated above can be applied, for example, to a door lock switch for a motor vehicle.
Such a door lock switch according to the prior art is generally disposed with a power window switch side by side on an armrest of the driver's seat, and there is a danger that the door lock switch is unintentionally operated. Especially because the door lock switch is located near a power window switch and often looks alike, there is a danger that a driver unintentionally presses the door lock switch instead of the power window switch, thus releasing the door lock against his will. This often happens especially when the driver has to take a glance at switches and press the intended switch when he intends to open a window while driving . Likewise, there is a danger that a driver accidentally presses the power window switch for closing the window and gets his fingers caught by the window when he intended to release the door lock to get out of the car. Such accidental or unintended switch operation may develop into a serious accident and generate an extremely dangerous condition.
Even if the driver does not commit such a mistake in operating the switches, his fingers may accidentally touch the door lock switch, causing the door lock switch to operate when it should not, leading to an extremely dangerous condition.